This invention relates to an exhaust valve for a reciprocating internal combustion engine, such as a two-stroke Diesel engine, and comprising a valve mamber which opens to permit the outflow of gas from the combustion chamber of the engine cylinder by moving away from said chamber, and which is biased in the opening direction by the gas pressure in the combustion chamber and in the closing direction by an oppositely directed hydraulic pressure.
An Article "A novel approach to uniflow scavenge" in the periodical "Marine Propulsion", May 1980, page 13 describes an exhaust valve of this kind, the valve member of which is formed as a piston slide similar to the exhaust piston of the well-known opposed-piston engines, but actuated hydraulically rather than mechanically. A working chamber in a hydraulic actuating cylinder, the piston of which is connected to the slide, communicates with a pressure accumulator via a control valve which is kept closed during the compression and working strokes in the engine cylinder, thereby confining within the working chamber an amount of liquid, which provides the necessary back pressure for keeping the slide closed. When the control valve is opened, the gas pressure drives the slide outwardly whereby hydraulic liquid is transferred from the working chamber to the accumulator. The movement of the slide is retarded by switching the control valve to a throttling position, followed by complete closing of the valve so that the slide remains in its open position until the control valve is re-opened at the termination of the scavenging period, whereby the accumulator pressure moves the slide to its closed position. The control valve is then closed in order to hold the slide against the compression and ignition pressure.